What's this APU thing?
I thought you normally started both engines before pushback, to power systems, aircon, etc. And did a proper checklist.
If we're now talking again about starting the engines just before line-up and take-off.... we're back to an earlier thread about taxying with tugs (does "RB" remind you of something?).
With all the consequences, like huge bottlenecks on the entry point to the runway, when sumptin goes belly-up?
And, as said here, has anybody done a proper balance sheet?